Cardinal Flower (Lobelia cardinalis)

As you walk through the Arboretum's Marsh Area in August, you are likely to see a number of bright red flowers growing along the edge of Scarborough Creek. Cardinal Flower is one of nine species of the genus Lobelia that occur in Tennessee (Visit the UT Herbarium web site for more information about the other species in Tennessee.) Lobelia cardinalis is our only Lobelia with brilliant red flowers - however, one other red-flowered species (L. laxiflora) is found in southern Arizona. Cardinal Flower is found throughout eastern North America and adjacent Canada, and across the southwest to California. Its typical habitat is along streams, ponds, and other wetland situations.

The two-lipped, tubular flowers have three prominent lobes on the lower lip and two smaller lobes on the upper lip. Hummingbirds and butterflies are major pollinators. The common name is purportedly a reference to the bright red robes of Roman Catholic Cardinals. Although the plant has been used for a variety of medicinal purposes, its extracts contain as many as 14 poisonous alkaloids. A planting of Cardinal Flowers is present next to the Arboretum's Visitor Center.

Carolina Buckthorn or Indian Cherry(Rhamnus caroliniana)

Carolina Buckthorn is a native shrub or small tree that is especially conspicuous along Arboretum Drive, the Backwoods Trail, and the Crossroads Trail. It is found throughout the Southeast and ranges as far north as New York and as far west as Texas, Oklahoma, and Nebraska. This shrub is typically 10-15 ft tall, but may grow up to 20-30 ft.

Its shiny green leaves (2-5 in. long) are somewhat paler below with prominent, parallel veins that curve a short distance along the margins. The small fuzzy brown buds are distinctive and have been described as being naked (i.e., do not have numerous bud scales). Carolina Buckthorn bears inconspicuous greenish-white flowers in May and June. The round, berry-like fruits (drupes) are initially red in August but turn dark blue to black in the fall. A variety of song birds feast on these sweet juicy fruits. Although Carolina Buckthorn has no thorns, its common name reflects the fact that many members of the genus Rhamnus have thorny twigs.

Northern Catalpa (Catalpa speciosa)

Two large Northern Catalpa trees (also known as Indian Bean Tree or Cigar Tree) can be seen along Arboretum Drive near the Juniper Collection. The genus name Catalpa purportedly comes from a Cherokee Indian word for "bean tree" - the dark brown seed pods that become conspicuous in mid- to late summer have a long (8-20 in.), bean-like shape. The showy white, bell-shaped flowers highlighted with yellow and purple markings in the center appear in late May. Northern Catalpa grows to heights of 40-70 ft. Its large (6-12 in. long), heart-shaped leaves are rounded to cordate at the base and pointed at the tip.

Catalpa belongs to the Bignoniacea family, which also includes Cross Vine and Trumpet Creeper. The natural range for Northern Catalpa includes western Tennessee and other parts of the Central Mississippi Valley. It has been widely planted in urban areas as an ornamental and shade tree. The brittle wood resists rot and in the past has been used for railroad ties, fence posts, etc.

Eastern Red Cedar/Old Field Juniper
(Juniperus virginiana)

Eastern Red Cedar (also known as Old Field Juniper) is a small to medium sized coniferous tree with scale-like or awl-like leaves and bluish, berry-like fruits. It is widespread throughout the eastern U.S. and adjacent Canada. It invades open areas that have been disturbed by fire or cleared for agriculture. Individual trees may persist in older forests for many years. As you walk the trails at the Arboretum, you may see older Eastern Red Cedar trees that indicate clearing for past land use or smaller trees that have developed in forest openings.

Several different cultivars of Juniperus virginiana can be found in the Juniper Collection near the Program Shelter. The “Cedar barrens” behind Jefferson Middle School in Oak Ridge is an example of an area currently dominated by Eastern Red Cedar.

In late winter, Eastern Red Cedar produces a copious amount of pollen that is a potent allergen. The female cones develop into bluish “berries” with a waxy coating. The fruits provide an important winter food source for birds which disperse the seeds widely. The aromatic wood repels insects and is used for lining cedar chests and as fence posts. The tree also is planted for windbreaks and is used for making pencils and for Christmas Trees in the South. The Forest Resources Center crews utilize these trees for fence posts, bird houses, and kindling in the operations of the Center. Eastern Red Cedar is an alternate host for cedar-apple rust and should not be planted near fruit trees. Berries from a related species, Juniperus communis (Common Juniper), are used to flavor gin.

Japanese Cedar (Cryptomeria japonica)

Two large, impressive trees in the Arboretum’s Conifer Collection are the Japanese Cedars on the hill above the Program Shelter and the Oak Collection. These are not true cedars, but belong to the Cupressaceae family, which also includes junipers, bald cypress, arborvitae, and redwoods. A dwarf form of this tree can be found in the Dwarf and Unusual Conifer Collection. This ancient tree is the National tree of Japan and is also called “Temple Tree” for its use in building the centuries-old Shinto temples. It has a pyramidal, conical shape with somewhat pendulous branches. It is evergreen and grows 50-60 ft high — though old trees as high as 230 ft have been reported.

Japanese Cedar has blue-green, needle-like leaves and a red-brown bark that peels off in vertical strips. The seed cones are globular. It is a forest tree native to Japan (16% of Japanese managed forests are of Japanese Cedar). It has a wide variety of uses in construction and the manufacture of furniture, utensils, and paper. Japanese Cedar is cultivated as an ornamental, landscape tree, and is frequently used for Bonsai.

Black Cherry (Prunus serotina)

Black Cherry is commonly found along many trails at the Arboretum. Under a dense forest canopy, the trees are often small and shrub-sized with few flowers or fruits. Larger trees can be found in more open areas such as forest edges or forest openings where the fast-growing black cherries can better compete for light.

Black cherries which are relished by birds and other small animals have been ripening this past week. Birds distribute large numbers of the seeds widely. Trees loaded with fruit can be seen near the Program Shelter next to the dogwood plantings and just below the Shade Tree Orchard. The bark of young Black Cherries is smooth and reddish brown or gray with well-defined horizontal lenticels.

Older trees have more furrowed, platy bark which turns up at the edges. In the past, extracts of the bark have been used in cough medicines and various tonics. The leaves and twigs contain a cyanide compound which has been implicated in the death of horses and other livestock. The wood is used extensively for veneer, furniture, and lumber.

American Chestnut (Castanea dentata)

American Chestnut was a dominant tree in the eastern deciduous forest before the early 1920's. Sources indicate that as many as one in four trees in our forests may have been American Chestnut. It provided durable lumber, tannins, and edible nuts. The arrival of the Chestnut Blight in the early 1900's, however, resulted in the virtual elimination of this species by the 1940's. Old stumps and root sprouts of American Chestnut were present in Arboretum forests until recently and were the basis for developing and naming the Lost Chestnut trail. These remnants have now mostly disappeared, although root sprouts may still be present in the area.

In a talk at the UTAS annual meeting in November 2011, Bryan Burhans, President and CEO of the American Chestnut Foundation described the Foundation's efforts to develop blight resistant hybrid chestnuts from crosses between American Chestnut and Chinese Chestnut. A principal challenge is to develop hybrids that have the blight resistance of Chinese Chestnut but otherwise possess characteristics of the American Chestnut, including rapid growth, production of large numbers of chestnuts, and the ability to compete successfully in natural forest environments with other native species. Hybrids that are more than 90% American Chestnut are currently being tested at many different locations in the Eastern and Midwestern US, with the understanding that different hybrids that can adapt to different geographic regions and habitats will be needed.

UT researchers have been conducting studies to identify blight resistant strains of American Chestnut and to develop blight resistant hybrids. A number of studies have evaluated performance of American Chestnut planted on abandoned coal strip mines, both to evaluate the resistance of hybrids to Chestnut blight and to determine their potential use for reclamation. A related study at the UT Forest Resources Research and Education Center in Oak Ridge is evaluating the performance of native trees, including American Chestnut, on quarry spoils. The study is examining the effects of overburden preparation, response of trees to nitrogen fertilization and liming, and the success of pioneer vs later successional trees. Effects of the treatments on ecosystem processes such as changes in soil chemistry and photosynthetic rates are being documented.

Chinese Chestnut (Castanea mollissima)

A native of China and Korea, the Chinese Chestnut has been planted extensively in the US as an ornamental. It is resistant, but not immune, to the chestnut blight which virtually eliminated the American Chestnut (Castanea dentata) from the Eastern Deciduous Forest of North America. Chinese Chestnut cultivars are being crossed with American Chestnuts in a breeding program to develop a hybrid resistant to the chestnut blight.

At this time of year, the ground below two Chinese Chestnut trees upslope from the Arboretum Visitors Center is littered with large spiny chestnut fruits (burs), up to 3 in. long and over one inch in diameter, containing one to three shiny brown nuts. These edible nuts are flattened on one or two sides and very attractive to squirrels and other wildlife. Once they have fallen, they can pose a significant litter problem.

Chinese Chestnut is monoecious, bearing male and female flowers on long (4-5 in.), fragrant, yellowish-white catkins in June. As with other members of the genus Castanea, the male flowers make up the upper portion of the catkins, while a small number (1-3) of inconspicuous female flowers occur at the base. The undersides of the glossy toothed leaves (5-8 in. long) and the twigs are densely pubescent.

Chinese Chestnut can be distinguished from the native American Chestnut by the dense pubescence on its twigs and the undersides of its leaves (American Chestnut leaves and twigs are essentially glabrous) and the number of nuts in each bur - 2 to 3 versus 1 (rarely 2). In addition, the spiny bracts surrounding the nuts are larger for the Chinese Chestnut.

Chinese Mountain Ash (Sorbus koehneana)

A large tree near the end of Marsh Road in the Central China Collection is an interesting representative of the Mountain Ash genus (Sorbus). Chinese Mountain Ash is a native of temperate regions in China. It is usually described as a large shrub or small tree that has pinnately compound leaves. Our specimen appears to be unusually large for the species. In the spring, Chinese Mountain Ash bears clusters of white flowers. As the season progresses, the green berries develop into white fruits. Our native American Mountain Ash (Sorbus americana) is found in the mountains of East Tennessee. It is smaller than Chinese Mountain Ash and bears red berries. In Europe, members of this genus are referred to as Rowans.

Chinese Parasol Tree (Firmiana simplex)

One of the interesting trees in the Shade Tree Collection at the Arboretum is a Chinese Parasol Tree. In late October and early November, its large leaves (up to 12 in. wide) are bright yellow gradually turning to brown. This native of China, Japan, and southeast Asia, a member of the Cacao (cocoa) family (Sterculiaceae), is planted as an ornamental tree in the Southeastern US and has become naturalized in a few locations. The Chinese Parasol Tree grows rapidly to heights of 30 to 50 ft and develops vigorous sprouts around its base that need to be cut back periodically. This sprouting often results in multiple trunks. The wood has been used to make furniture and coffins. Medicinal uses have included salves and lotions to reduce swelling and treat such conditions as hemorrhoids, carbuncles, and sores.

The relatively smooth, light-colored bark has a greenish tint and has been used for fiber to make cordage and cloth. The female flowers develop into brown pods which split into four sections and are said to resemble parasols.

Chinese Quince (Pseudocydonia sinensis)

As you walk from the Program Shelter along the edge of the Arboretum's Shade Tree Collection in early November, you may notice a tree bearing large globular fruits, many of which have fallen to the ground. As its name indicates, Chinese Quince is a native of Eastern China. Although related to other European and Asian Quinces, it has been placed in a separate genus. It may grow from 10 to more than 40 ft in height and develops a dense, twiggy crown. The alternate, simple, dark green leaves have serrated margins and turn yellow to red in the fall. The attractive fluted bark is flaky and is said to resemble the bark of Sycamore. Chinese Quince has been used to treat such illnesses as asthma, the common cold, and tuberculosis. The hard, dark red wood is used in making a variety of items such as knife handles, wooden bowls, musical instruments, and picture frames.

A member of the Rosaceae plant family, it produces fragrant, pink flowers in the spring - our specimen was in flower at the end of March in 2011. The large (as much as 7 in. long and 4 in. wide), astringent fruits become sweeter after frost and are used for making jams, syrups, and liqueurs.

Chinese Privet (Ligustrum sinense)

Chinese Privet, an invasive, non-native shrub or small tree, is found in a variety of habitats at the Arboretum, including wetlands, upland forests, and disturbed areas. It is a native of Southeast Asia that was introduced into the US as an ornamental in the mid-1800s and has subsequently spread throughout the East and Southeast. Once established, it produces vigorous root sprouts and can outcompete native species, completely taking over an area. Its abundant dark blue fruit is eaten by birds and other wildlife, and the seeds are widely dispersed by them.

A member of the Olive Family (Oleaceae), Chinese Privet is semi-evergreen with opposite leaves, gray bark, and dense clusters of fragrant white flowers in the spring. At the Arboretum, it is especially conspicuous in forest edges along Arboretum Drive, Cemetery Ridge trail, and as scattered clumps along Scarborough Creek. It is difficult to control, as it rapidly sprouts back from roots and stumps when cut back. Its leaves have a high content of phenolic compounds that protect it from insects and other herbivores. The UT Forest Resources Center, in cooperation with UT faculty, is presently engaged in the testing of new herbicides to help eradicate privet and other invasive, non-native plants.

Christmas Fern (Polystichum acrosticoides)

A walk along the Arboretum trails during winter months finds very few green plants on the forest floor. The evergreen leaves (fronds) of Christmas Fern, however, persist throughout the winter months. New growth is initiated in early April when young leaves, known as fiddleheads, emerge. Although the fiddleheads of other ferns are considered delicacies, the scaly nature of the leaf rachises of Christmas Fern detract from their culinary appeal.

In late May and early June, clusters of brown sori (spore-bearing structures) are found on the underside of the upper 1/3 of the fertile fronds (leaves). Christmas fern gets its common name from its stocking-shaped leaflets along the pinnately compound leaves and from the historical use of the leaves as Christmas decorations. The species is widely distributed in forests of the Central and Eastern U.S. It is frequently planted for groundcover, especially in shady areas and on slopes. Because it is evergreen and has a well-developed underground rhizome system, it is used in landscaping to help control erosion.

Cilician Fir (Abies cilicica)

The Dwarf and Unusual Conifer collection adjacent to Valley Drive has a number of interesting conifers from other parts of the world. One of these, Cilician Fir, is a native of Turkey, Lebanon, and Syria. Its name reflects the geographic region from which it comes. The Plains of Cilicia extend along the Mediterranean coast of Turkey north and northeast of the Island of Cyprus and adjacent to the Taurus Mountain. A narrow gorge through the mountain range is known as the Cilician Gates and provides access to the Anatolia Plateau. This gorge has served as a major military and commercial route for centuries.

In its native habitat Cilician Fir is a component of degraded forests at higher elevations (3200 to 7200 ft). The tree has a conical shape and may reach heights of 100 ft.

It has been used as a diuretic and to treat wrinkles, extract worms, and promote hair growth. Cilician Fir has been used for a variety of other purposes such as lumber, masts for boats, flag poles, and joinery.

Its grayish-brown bark is covered with resin pockets. The flat, evergreen needles, 1 to 1.5 in. long, are shiny green above, and underneath have two white bands formed by several lines of stomata. The upright cylindrical cones have resinous scales. The resin from these cone scales has been collected and used in mummification and in folk medicine as an antiseptic, for treating bacterial and viral infections, and for its anti-inflammatory, and antipyretic properties.

Climbing Fern (Lygodium palmatum)

Climbing Fern is an unusual plant found at a few locations on the Arboretum. It appears to be more of a vine than a fern. Its compound leaf (frond) consists of a twining, vine-like stalk (rachis) with sterile, palmate leaflets along its base and smaller fertile leaflets bearing sporangia toward its tip. The sterile leaflets (pinna) consist of a pair of palmate pinnules each of which has 5-10 lobes. These sterile pinna are evergreen and persist through the winter, while the fertile pinna die back. The climbing leaf can reach 3 meters in length. The genus Lygodium is mainly tropical, with L. palmatum being the only member native to North America. Two related species (L. japonicum and L. microphyllum) have been introduced into the southern US and are considered invasive. Climbing Fern is found throughout the eastern US, ranging from New England south to Florida, and west to the Mississippi River and Michigan's Upper Peninsula. It is locally rare in most areas, but may be most abundant on the Cumberland Plateau. In the past it was collected extensively for Christmas decorations in New England and is considered a species requiring protection in many states.

Cranefly Orchid (Tipularia discolor)

If you look carefully along a number of our Arboretum trails, you may be fortunate enough to see an inconspicuous orchid that blooms in mid- to late July. The leaves of the Cranefly Orchid, which develop late in the fall, are distinctive in being green on the upper surface and purple below. The leaves persist during the winter months allowing the plant to photosynthesize during the season when sunlight reaches the deciduous forest floor. In the spring, the leaves break down and are absent at the time of flowering. Tipularia discolor, the only member of its genus in North America, is found in many parts of Tennessee and is distributed from southern New England, south to Florida, and west as far as Texas.

Crossvine (Bignonia capreolata)

Crossvine is one of three members of the Bignoniaceae plant family found in our area the other two being Catalpa (the bean tree) and Trumpet Creeper (Campsis radicans), both of which flower later in the year. Crossvine blooms toward the end of April and the first week of May. It is especially conspicuous on trees near Scarborough Creek along Old Kerr Hollow Road and in several places along the Cemetery Ridge Trail. It can also be seen driving along the Pellissippi Parkway as one approaches the Arboretum from Oak Ridge.

Crossvine can grow to more than 50 ft in length. Its compound leaves have three leaflets, the terminal one modified into tendrils that enable it to climb. These leaf characteristics differentiate it from Trumpet Creeper which has many leaflets, no terminal tendrils, but aerial rootlets for climbing. Crossvine has orange-red flowers while those of Trumpet Creeper are red. The tubular flowers of both Crossvine and Trumpet Creeper attract hummingbirds at different times of the growing season. Crossvine derives its common name from the fact that the pith of a cut stem often appears as a dark, cross-like center.

Cucumber Tree (Magnolia acuminata)

Pinkish colored fruits of the Cucumber Tree near the entrance to the Visitors Center are apparent in August. These cone-like fruits are initially green and said to resemble cucumbers, hence the common name. The yellow flowers that appear in late April consist of six greenish-yellow tepals (sepals and petals are undifferentiated). The fruits mature in late summer to early autumn, producing reddish-orange seeds which may persist into winter.

Cucumber Tree is a native of Eastern North America ranging from southern Ontario to northern Florida. The wood is used for furniture, plywood, containers, and pallets. One source says the fruits have been used as flavoring for whiskey. The bark was used for a variety of medicinal purposes by the Cherokee and Iroquois peoples.

Cumberland Azalea
(Rhododendron cumberlandense)

The Arboretum has many plantings of Azaleas and other Rhododendrons, many of which are hybrids that have been developed for horticultural use. Most of these have bloomed in May. Cumberland Azalea (Rhododendron cumberlandense), however, is a native species which is found on the Cumberland Plateau and in the mountains of Kentucky, Tennessee, North Carolina, Northern Georgia and Alabama. A showy example of this Azalea, can be seen in bloom near the Visitors Center in early June. This specimen was transplanted from the Cumberland Plateau several years ago.

Cumberland Azalea is similar to the Flame Azalea (R. calendulaceum) found at higher elevations in the Smokies and along the Blue Ridge Parkway. These two species along with other azaleas form hybrid swarms on Gregory Bald in the Smokies. The orange to red flowers of Cumberland Azalea are smaller than those of Flame Azalea and appear after the leaves are fully expanded.

Hinoki Cypress (Chamaecyparis obtusa)

A variety of trees belonging to the plant family Cupressaceae are commonly called "Cypress." At the Arboretum, several plantings in the Conifer Collection and the Dwarf and Unusual Conifer Collection belong to the genus Chamaecyparis and are known as Cypress or False Cypress. The Hinoki Cypress is a native of Japan and Taiwan. It has scale-like leaves borne on spreading branches that are in flattened planes. Dwarf cultivars of this species are commonly used in landscaping. An example of one of these dwarf cultivars is Chamaecyparis obtusa 'Filicoides', which can be seen in the Dwarf and Unusual Conifer Collection.

Leyland Cypress (x Cupressocyparis leylandii)

Leyland Cypress is a readily recognizable tree that is commonly used for landscaping in our area. Three well-developed specimens planted in 1967 are present in the Arboretum's Conifer Collection, and others are planted at the junction of Arboretum Drive and Valley Road. Leyland Cypress is fast-growing (3-4 ft. a year) and is used for hedges, screens, windbreaks, and Christmas trees. It was developed as a cross between two species belonging to different genera - Monterey Cypress (Cupressus macrocarpa) from Northern California and the Nootka False Cypress (Chamaecyparis nootkatensis) from the Pacific Northwest. The trees in the Conifer Collection are the 'Green Spire' cultivar, and those at Arboretum Drive are the 'Leighton Green' cultivar.

'Green Spire' is fast growing, reaching heights of 70 to 100 ft. It has a columnar form and dense dark green to blue-green foliage borne on flattened quadrangular branchlets. The 'Leighton Green' cultivar, developed at the Leighton Hall estate in Wales, is from a cross between a male Nootka False Cypress and a female Monterey Cypress. It has thick, dark green, scale-like foliage, and an oval to columnar form. Although 'Leighton Green' may produce viable seeds (uncommon for a cross between two genera), it is usually propagated from cuttings. It's fast growth rate and form make it attractive for use as Christmas trees.

Sawara Cypress (Chamaecyparis pisifera)

Sawara Cypress, considered a sacred tree in Japan, is a valuable timber species in that country. Although the original species may grow as high as 60 ft, many of the cultivars have been selected to produce dwarf plants that are used extensively in landscaping. A good example present in the Conifer Collection is Golden Threadleaf Sawara Cypress (Chamaecyparis pisifera 'Filifera Aurea Nana'). It has drooping yellow, threadlike foliage and reddish-brown bark that peels on older trees. This cultivar is generally described as a dwarf form, but our specimen is much taller. The Cupressaceae is a large family that includes 18 genera and many familiar plants at the Arboretum such as Junipers, Cedars, and Bald Cypress.